1. Field of the Invention
This invention relates generally to the field of automatic swimming pool cleaners, and more particularly, to cleaners of the type for submerged and generally random travel along the floor and sidewalls of a swimming pool to dislodge and collect debris.
2. Description of the Related Art
A swimming pool normally includes a water filtration system for removing dirt and debris from the pool water. Such filtration systems typically include a circulation pump which is installed outside the swimming pool and a piping system for coupling the circulation pump to the swimming pool. The circulation pump draws water from the swimming pool for delivery through the piping system to a filter unit.
One or more baskets are located in the piping system upstream from the filter unit to catch larger debris, such as leaves and the like; the filter unit functions to separate dirt and fine debris from the water. The water is then re-circulated by the pump back to the swimming pool.
A conventional water filtration system is satisfactory for removing dirt and debris of a relatively small size that is suspended in the water, but it is not designed to remove larger debris. Such systems depend on the aforementioned baskets to prevent larger debris from reaching the filter. However, it is generally advisable to clean out such baskets regularly to avoid the possibility that they may become clogged, blocking the flow of water through the pipes and resulting in damage to the circulation pump. Moreover, a conventional water filtration system is not designed to remove silt and debris which tends to settle irrespective of size onto the floor and sidewalls of a swimming pool.
To address the foregoing problems, automatic swimming pool cleaners for cleaning the floor and sidewalls of a swimming pool are well known.
There are generally four types of pool cleaners in the pool cleaning market: pressure or return side cleaners; suction cleaners; electric cleaners and in-floor cleaners.
Suction side cleaners connect to the pool's skimmer and utilize the sucking action of the water being drawn from the pool by the filter pump to vacuum debris. These cleaners do not sweep, nor to they employ a collection bag, as demonstrated by U.S. Pat. No. 5,001,600 (Parenti, et al.). Instead, large debris vacuumed by the suction side cleaners is deposited in the skimmer or pump basket, while sand and silt that is small enough to pass through the skimmer is captured in the pool's filter.
In-floor cleaners comprise pop-up sprinkler heads built into the floor of the pool and are not generally competitive with pressure, suction or electric sweep cleaners.
Electric cleaners include an electrical motor and attach to an electric cord that extends into the swimming pool. These cleaners operate much like a household vacuum cleaner and may include a filter or collection bag to collect debris. However, the sweeping action of electric cleaners is limited to a roller or brush positioned under the cleaner and the cleaner does not act as roving return lines for chemically treated or heated pool water. Because they are very costly, they have never been a significant factor in the residential in-ground pool cleaner market.
Generally, "pressure" or return-side cleaners perform superior cleaning over the other three types of cleaners because: Pressure cleaners both vacuum and sweep; Pressure cleaners act as a roving return line to circulate pool chemicals and heated water throughout the pool; Pressure cleaners to not interfere with pool skimmer operation; and Pressure cleaner have a collection bag to avoid the risk of clogging the pool's skimmer or pump basket and filter with debris.
One significant difference in such types of cleaners is the use of a debris bag in the pressure-type cleaners. Pressure-type cleaners use pressurized water from a pump into the cleaner to sweep and collect debris into a bag carried by the cleaner. This means that the bag itself has a weight, buoyancy, and a weight factor that changes when debris collects in the bag. The cleaner must be able to traverse the entire pool without being toppled. Weight is added to the bag when debris is collected in the bag, changing the weight of the bag as the cleaner moves in the pool.
In a pressure cleaner, the influx of water into the cleaner affects the manner in which the cleaner acts under water. The buoyancy of objects is also a significant consideration in developing pressure cleaners and is affected by the component in the cleaner and the water inflow and action of the water within the cleaner. These considerations are not present in electric cleaners or suction cleaners.
Pressurized cleaners can be characterized into at least two categories--those requiring a booster pump and those which do not. Booster pumps are used in conjunction with the pools skimmer pump to provide pressurized water to the cleaner at a rate sufficient to operate the cleaner effectively.
One particular type of known automatic pressure cleaner is shown and described in U.S. Pat. Nos. 3,822,754, 3,936,899, and 4,558,479. This type of cleaner has three wheels positioned in a skewed triangular arrangement on the outside of a housing, with the housing having a front nose set angularly with respect to the direction of cleaner movement. An open and generally vertically oriented suction mast defines a flow path through the housing with a collection bag mounted at the upper end.
This type of cleaner operates on pressurized water that is supplied to the cleaner through a supply hose. The water is used in part to drive the blades of a turbine which, in turn, rotates two or more of the wheels, and in part to induce a flow of pool water upwardly through the suction mast and into the collection bag. A portion of the pressurized water is also supplied through a sweep hose jet to a sweep hose and through a thrust jet, both at the rear of the cleaner. A booster pump may be used to generate added water pressure for the cleaner, because the circulation pump normally used in most swimming pool filtration systems does not create sufficient water pressure for all of the above purposes.
In operation of this type of cleaner, the drive wheels and thrust jet propel the cleaner along the floor and sidewalls of the swimming pool. When the pool cleaner reaches an obstruction preventing further direct forward travel, the skewed drive wheels and angled front nose of the cleaner housing imparts a turning movement, causing the cleaner to turn and continue travel in a different direction. Alternatively, when the cleaner travels along the pool floor and reaches a smoothly curved region merging with a sidewall, the cleaner tends to travel through the curved region and crawl at least part way up the pool sidewall with suction-assisted wheel traction until the cleaner falls by gravity back to the floor of the pool. A ballast float mounted at the upper rear of the cleaner helps assure that the cleaner will land upright on the pool floor and resume travel in a forward direction. As the cleaner travels around the pool, it vacuums the larger debris up through the suction mast into the collection bag. At the same time, the whipping action of the sweep hose sweeps any silt and smaller debris into suspension so that it can be filtered out by the pool's filtration system.
While submerged pool cleaning devices of the foregoing type have performed in a generally satisfactory manner, certain shortcomings have been observed in available commercial equipment. For example, existing cleaners have been constructed on the premise that it is advantageous for all three wheels to be driven by the turbine. In order to accomplish this, however, the cleaner uses a drive train for the wheels which either has been partly exposed to potential jamming or damaged from contact with pool debris, or has used internal belts that have not proved highly reliable. In addition, existing cleaners have not typically been capable in practice of climbing the sidewalls of a swimming pool as aggressively as desired. For example, instead of the cleaner turning when it reaches a relatively sharp transition between the pool floor and a sidewall, it would be desirable for the cleaner to continue its forward travel and climb the sidewall. Further, it would be desirable for the cleaner to climb the sidewall nearly all the way to the waterline.
In addition, cleaners of the type listed in the '479 patent have required a booster pump be installed in order to generate sufficient pressure to the apparatus to power the device about the pool. In older pool installations, the pool's cleaning system may require retrofitting to install the booster pumps in order to properly operate the device.
Accordingly, a need exists for an improved automatic swimming pool cleaner of the type adapted for submerged travel over pool surfaces operating effectively without a booster pump. The present invention fulfills these and other needs.